Step 1: Understanding the Concept:
Anticancer agents derived from plants are known as vinca alkaloids. They were first isolated from the Madagascar periwinkle.
Step 2: Detailed Explanation:
1. Catharanthus roseus: Formerly known as \textit{Vinca rosea}. It contains over 70 alkaloids, including the dimeric indole alkaloids Vincristine and Vinblastine.
2. Usage: These are critical chemotherapy drugs used to treat various cancers, including leukemia, Hodgkin's lymphoma, and solid tumors.
3. Others: \textit{Artemisia} gives antimalarials. \textit{Rauwolfia} gives antihypertensives. \textit{Podophyllum} gives resin for warts/cancer but not these specific alkaloids.
Step 3: Final Answer:
The periwinkle plant, \textit{Catharanthus roseus}, is the commercial biological source of these life-saving anti-tumour alkaloids.